Ashley Fox is an MEP for South West England, and is the leader of Britain’s Conservative MEPs.

When the Brexit dust finally settles, I believe last week’s inner cabinet meeting at Chequers will be seen as a key staging post in Britain’s exit from the European Union.

The Prime Minister defied critics by securing broad agreement for her vision of a comprehensive free trade agreement, under which Britain and the EU remain in regulatory alignment in key areas while diverging where our interests differ.

Equally significant, here in Brussels Donald Tusk, the President of the European Council, dismissed it almost immediately. In a comment aimed squarely at EU27 capitals tempted to see Theresa May’s plan as a sensible starting point for negotiations, he claimed it was based on “pure illusion”, despite not being in possession of any details.

Even Commission President Jean Claude Juncker had declined to react, stating: “I am not commenting on the outcome of the Chequers meeting until I know the exact conclusions.”

Tusk quickly reached for a sound bite because the Prime Minister’s proposal threatened the EU27’s outward show of unity. At a time when an increasing number of voices on the continent are privately urging EU negotiators to adopt a more constructive approach, he understands the importance of entering negotiations on the future relationship with one voice.

However, at some point the EU must begin to regard Britain, not as a departing member, but as one of the world’s largest economies with whom a comprehensive free trade deal would be of benefit to both sides. In that context May’s practical plan makes absolute sense.

To illustrate, take a look at CETA, the EU/Canada trade deal often quoted as a starting point for our forthcoming talks. The advantages secured by Canada which, in the current climate, would no doubt be branded “cherry picking” by Tusk if sought by Britain, include:

The agreement removes 98 per cent of tariff lines from Canadian goods exported to the EU, including industrial goods, agriculture and agri-food products, fish and seafood;

Co-operation between Canadian and EU regulators ensures “compatible” regulations on a wide range of goods;

Canadian companies can bid for all EU government procurement contracts;

Canadian suppliers in most service sectors are on an equal footing with EU service providers;

Canada maintains the right to review major acquisitions from EU investors and is able to regulate in the public interest;

Canada has excluded from the trade deal services classed as “fundamental to the social fabric”. These include health care and public education.

All this while Canada remains free to negotiate its own trade deals with other countries. It makes no payments to the EU and is not required to sign up to unchecked freedom of movement.

The UK is already in full conformity with EU and will be able to go much further when detailed negotiations on the future relationship begin. However, we are not there yet and in the meantime expect more critical sound bites from Tusk tomorrow when the Prime Minister fleshes out her proposals.

In contrast, he remained conspicuously silent on Monday when Jeremy Corbyn cast aside principle and revealed his sudden fondness for the customs union.

Not only would Labour’s opportunistic proposal diminish Britain by stopping us signing free trade deals with countries across the globe – and bind us to the EU’s system of tariffs and hand Brussels complete control of our trade policy – it assumes the EU would allow a Labour government to subsidise industries and pursue a programme of state ownership. Both these are football-sized cherries Corbyn has no chance of picking.

However, Tusk is happy to overlook this while Labour continues edging towards the EU’s preferred outcome of Britain remaining in a Norway-style relationship with Brussels, paying for tariff-free access to the single market and accepting rules over which it has no say.

The Prime Minister understands the position and has made clear she will not be diverted from the course set in her Florence speech. The accelerator was pressed at Chequers and will speed us past Corbyn’s customs union wrong turn.